Pub Date : 2024-07-17DOI: 10.1038/s44306-024-00036-1
Yihong Fan, Zach Cresswell, Yifei Yang, Wei Jiang, Yang Lv, Thomas J. Peterson, Delin Zhang, Jinming Liu, Tony Low, Jian-Ping Wang
Topological semimetal materials have attracted a great deal of attention due to their intrinsic strong spin-orbit coupling, which leads to large charge-to-spin conversion efficiency and novel spin transport behaviors. In this work, we have observed a bilinear magnetoelectric resistance (BMER) of up to 0.0034 nm2A−1Oe−1 in a single layer of sputtered semimetal Pt3Sn at room temperature. Being different from previous works, the value of BMER in sputtered Pt3Sn does not change out-of-plane due to the polycrystalline nature of the Pt3Sn layer. The observation of BMER provides strong evidence of the existence of spin-momentum locking in the sputtered polycrystalline Pt3Sn. By adding an adjacent CoFeB magnetic layer, the BMER value of this bilayer system is doubled compared to the single Pt3Sn layer. This work broadens the material system in BMER study, which paves the way for the characterization of topological states and applications for spin memory and logic devices.
{"title":"Observation and enhancement of room temperature bilinear magnetoelectric resistance in sputtered topological semimetal Pt3Sn","authors":"Yihong Fan, Zach Cresswell, Yifei Yang, Wei Jiang, Yang Lv, Thomas J. Peterson, Delin Zhang, Jinming Liu, Tony Low, Jian-Ping Wang","doi":"10.1038/s44306-024-00036-1","DOIUrl":"10.1038/s44306-024-00036-1","url":null,"abstract":"Topological semimetal materials have attracted a great deal of attention due to their intrinsic strong spin-orbit coupling, which leads to large charge-to-spin conversion efficiency and novel spin transport behaviors. In this work, we have observed a bilinear magnetoelectric resistance (BMER) of up to 0.0034 nm2A−1Oe−1 in a single layer of sputtered semimetal Pt3Sn at room temperature. Being different from previous works, the value of BMER in sputtered Pt3Sn does not change out-of-plane due to the polycrystalline nature of the Pt3Sn layer. The observation of BMER provides strong evidence of the existence of spin-momentum locking in the sputtered polycrystalline Pt3Sn. By adding an adjacent CoFeB magnetic layer, the BMER value of this bilayer system is doubled compared to the single Pt3Sn layer. This work broadens the material system in BMER study, which paves the way for the characterization of topological states and applications for spin memory and logic devices.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00036-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141639671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-02DOI: 10.1038/s44306-024-00035-2
Jiahao Wu, Jiacheng Liu, Zheyu Ren, Man Yin Leung, Wai Kuen Leung, Kin On Ho, Xiangrong Wang, Qiming Shao, Sen Yang
Frequency conversion is a widely realized physical process in nonlinear systems of optics and electronics. As an emerging nonlinear platform, spintronic devices have the potential to achieve stronger frequency conversion. Here, we demonstrated a microwave frequency conversion method in a hybrid quantum system, integrating nitrogen-vacancy centers in diamond with magnetic thin film CoFeB. We achieve a conversion bandwidth ranging from 0.1 to 12 GHz, presenting an up to 25th order frequency conversion and further display the application of this method for frequency detection and qubits coherent control. Distinct from traditional frequency conversion techniques based on nonlinear electric response, our approach employs nonlinear magnetic response in spintronic devices. The nonlinearity, originating from the symmetry breaking such as domain walls in magnetic films, presents that our method can be adapted to hybrid systems of other spintronic devices and spin qubits, expanding the application scope of spintronic devices and providing a promising on-chip platform for coupling quantum systems.
{"title":"Wideband coherent microwave conversion via magnon nonlinearity in a hybrid quantum system","authors":"Jiahao Wu, Jiacheng Liu, Zheyu Ren, Man Yin Leung, Wai Kuen Leung, Kin On Ho, Xiangrong Wang, Qiming Shao, Sen Yang","doi":"10.1038/s44306-024-00035-2","DOIUrl":"10.1038/s44306-024-00035-2","url":null,"abstract":"Frequency conversion is a widely realized physical process in nonlinear systems of optics and electronics. As an emerging nonlinear platform, spintronic devices have the potential to achieve stronger frequency conversion. Here, we demonstrated a microwave frequency conversion method in a hybrid quantum system, integrating nitrogen-vacancy centers in diamond with magnetic thin film CoFeB. We achieve a conversion bandwidth ranging from 0.1 to 12 GHz, presenting an up to 25th order frequency conversion and further display the application of this method for frequency detection and qubits coherent control. Distinct from traditional frequency conversion techniques based on nonlinear electric response, our approach employs nonlinear magnetic response in spintronic devices. The nonlinearity, originating from the symmetry breaking such as domain walls in magnetic films, presents that our method can be adapted to hybrid systems of other spintronic devices and spin qubits, expanding the application scope of spintronic devices and providing a promising on-chip platform for coupling quantum systems.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00035-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141537066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-02DOI: 10.1038/s44306-024-00030-7
Rostyslav O. Serha, Andrey A. Voronov, David Schmoll, Roman Verba, Khrystyna O. Levchenko, Sabri Koraltan, Kristýna Davídková, Barbora Budinská, Qi Wang, Oleksandr V. Dobrovolskiy, Michal Urbánek, Morris Lindner, Timmy Reimann, Carsten Dubs, Carlos Gonzalez-Ballestero, Claas Abert, Dieter Suess, Dmytro A. Bozhko, Sebastian Knauer, Andrii V. Chumak
Quantum magnonics investigates the quantum-mechanical properties of magnons, such as quantum coherence or entanglement for solid-state quantum information technologies at the nanoscale. The most promising material for quantum magnonics is the ferrimagnetic yttrium iron garnet (YIG), which hosts magnons with the longest lifetimes. YIG films of the highest quality are grown on a paramagnetic gadolinium gallium garnet (GGG) substrate. The literature has reported that ferromagnetic resonance (FMR) frequencies of YIG/GGG decrease at temperatures below 50 K despite the increase in YIG magnetization. We investigated a 97 nm-thick YIG film grown on 500 μm-thick GGG substrate through a series of experiments conducted at temperatures as low as 30 mK, and using both analytical and numerical methods. Our findings suggest that the primary factor contributing to the FMR frequency shift is the stray magnetic field created by the partially magnetized GGG substrate. This stray field is antiparallel to the applied external field and is highly inhomogeneous, reaching up to 40 mT in the center of the sample. At temperatures below 500 mK, the GGG field exhibits a saturation that cannot be described by the standard Brillouin function for a paramagnet. Including the calculated GGG field in the analysis of the FMR frequency versus temperature dependence allowed the determination of the cubic and uniaxial anisotropies. We find that the total crystallographic anisotropy increases more than three times with the decrease in temperature down to 2 K. Our findings enable accurate predictions of the YIG/GGG magnetic systems behavior at low and ultralow millikelvin temperatures, crucial for developing quantum magnonic devices.
{"title":"Magnetic anisotropy and GGG substrate stray field in YIG films down to millikelvin temperatures","authors":"Rostyslav O. Serha, Andrey A. Voronov, David Schmoll, Roman Verba, Khrystyna O. Levchenko, Sabri Koraltan, Kristýna Davídková, Barbora Budinská, Qi Wang, Oleksandr V. Dobrovolskiy, Michal Urbánek, Morris Lindner, Timmy Reimann, Carsten Dubs, Carlos Gonzalez-Ballestero, Claas Abert, Dieter Suess, Dmytro A. Bozhko, Sebastian Knauer, Andrii V. Chumak","doi":"10.1038/s44306-024-00030-7","DOIUrl":"10.1038/s44306-024-00030-7","url":null,"abstract":"Quantum magnonics investigates the quantum-mechanical properties of magnons, such as quantum coherence or entanglement for solid-state quantum information technologies at the nanoscale. The most promising material for quantum magnonics is the ferrimagnetic yttrium iron garnet (YIG), which hosts magnons with the longest lifetimes. YIG films of the highest quality are grown on a paramagnetic gadolinium gallium garnet (GGG) substrate. The literature has reported that ferromagnetic resonance (FMR) frequencies of YIG/GGG decrease at temperatures below 50 K despite the increase in YIG magnetization. We investigated a 97 nm-thick YIG film grown on 500 μm-thick GGG substrate through a series of experiments conducted at temperatures as low as 30 mK, and using both analytical and numerical methods. Our findings suggest that the primary factor contributing to the FMR frequency shift is the stray magnetic field created by the partially magnetized GGG substrate. This stray field is antiparallel to the applied external field and is highly inhomogeneous, reaching up to 40 mT in the center of the sample. At temperatures below 500 mK, the GGG field exhibits a saturation that cannot be described by the standard Brillouin function for a paramagnet. Including the calculated GGG field in the analysis of the FMR frequency versus temperature dependence allowed the determination of the cubic and uniaxial anisotropies. We find that the total crystallographic anisotropy increases more than three times with the decrease in temperature down to 2 K. Our findings enable accurate predictions of the YIG/GGG magnetic systems behavior at low and ultralow millikelvin temperatures, crucial for developing quantum magnonic devices.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11219280/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141536332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-02DOI: 10.1038/s44306-024-00029-0
A. Dal Din, O. J. Amin, P. Wadley, K. W. Edmonds
In this review article, we summarize some recent key results in the development of antiferromagnetic spintronics. Current-induced switching of the Néel vector orientation has now been established in a wide range of antiferromagnetic films and antiferromagnet / heavy metal bilayers, as well as current-driven motion of antiferromagnetic spin textures. The latter are particularly promising due to their small size and topological stability, but reading their magnetic state presents challenges. We also focus on materials whose compensated spin arrangements (either collinear or noncollinear) are coexistent with a spin-split band structure, enabling first-order spintronic phenomena including giant and tunneling magnetoresistance, and the anomalous Hall effect. The resulting combination of efficient electrical readout mechanisms with the advantages of a near-zero net magnetization has potential to be transformative for spintronic applications.
{"title":"Antiferromagnetic spintronics and beyond","authors":"A. Dal Din, O. J. Amin, P. Wadley, K. W. Edmonds","doi":"10.1038/s44306-024-00029-0","DOIUrl":"10.1038/s44306-024-00029-0","url":null,"abstract":"In this review article, we summarize some recent key results in the development of antiferromagnetic spintronics. Current-induced switching of the Néel vector orientation has now been established in a wide range of antiferromagnetic films and antiferromagnet / heavy metal bilayers, as well as current-driven motion of antiferromagnetic spin textures. The latter are particularly promising due to their small size and topological stability, but reading their magnetic state presents challenges. We also focus on materials whose compensated spin arrangements (either collinear or noncollinear) are coexistent with a spin-split band structure, enabling first-order spintronic phenomena including giant and tunneling magnetoresistance, and the anomalous Hall effect. The resulting combination of efficient electrical readout mechanisms with the advantages of a near-zero net magnetization has potential to be transformative for spintronic applications.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00029-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141537068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
For the realization of magnon-based current-free technologies, referred to as magnonics, all-optical control of magnons is an important technique for both fundamental research and practical applications. Magnon-polariton is a coupled state of magnon and photon in a magnetic medium, expected to exhibit magnon-like controllability and photon-like high-speed propagation. While recent studies have observed magnon-polaritons as modulation of incident terahertz waves, the influence of magnon-photon coupling on magnon propagation properties remains unexplored. This study aimed to observe the spatiotemporal dynamics of coherent magnon-polaritons through time-resolved imaging measurements. BiFeO3 was selected as the sample due to its anticipated strong coupling between magnons and photons. The observed dynamics suggest that antiferromagnetic magnons can propagate over long distances, up to hundreds of micrometers, through strong coupling with photons. These results enhance our understanding of the optical control of magnonic systems, thereby paving the way for terahertz opto-magnonics.
{"title":"Sub-millimeter propagation of antiferromagnetic magnons via magnon-photon coupling","authors":"Ryo Kainuma, Keita Matsumoto, Toshimitsu Ito, Takuya Satoh","doi":"10.1038/s44306-024-00034-3","DOIUrl":"10.1038/s44306-024-00034-3","url":null,"abstract":"For the realization of magnon-based current-free technologies, referred to as magnonics, all-optical control of magnons is an important technique for both fundamental research and practical applications. Magnon-polariton is a coupled state of magnon and photon in a magnetic medium, expected to exhibit magnon-like controllability and photon-like high-speed propagation. While recent studies have observed magnon-polaritons as modulation of incident terahertz waves, the influence of magnon-photon coupling on magnon propagation properties remains unexplored. This study aimed to observe the spatiotemporal dynamics of coherent magnon-polaritons through time-resolved imaging measurements. BiFeO3 was selected as the sample due to its anticipated strong coupling between magnons and photons. The observed dynamics suggest that antiferromagnetic magnons can propagate over long distances, up to hundreds of micrometers, through strong coupling with photons. These results enhance our understanding of the optical control of magnonic systems, thereby paving the way for terahertz opto-magnonics.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00034-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141537077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the past decade, there has been a significant rise in the development of novel spintronic device architectures specifically designed to meet the demands of diverse biomedical applications. These advancements have notably focused on enhancing various bioassay detection techniques, including magnetocardiography and neural signal recording. Through collaboration within the spintronics community, these devices are rapidly transitioning from laboratory prototypes to practical applications, catering to diverse biomedical applications and benefiting both researchers and medical practitioners alike. In this review, we comprehensively explore the biomedical applications of spintronic devices, due to their inherent sensitivity to external magnetic fields, ease of fabrication into large arrays of nano/micro-sized devices within confined spaces, resilience under harsh environmental conditions, and high repeatability. Established spintronics devices that exploit various magnetoresistive effects have already been extensively deployed as magnetic biosensors for disease diagnosis, medical imaging, and bio-magnetic field detection, offering superior sensitivity and robustness. This review aims to provide peers with an up-to-date overview of spintronic devices in biomedical contexts while also commenting on future research trends and challenges. With advancements in nano/microfabrication techniques enhancing device robustness and magnetic field sensitivity, it is foreseeable that these spintronic devices could catalyze revolutionary transformations in healthcare.
{"title":"Spintronic devices for biomedical applications","authors":"Shahriar Mostufa, Shuang Liang, Vinit Kumar Chugh, Jian-Ping Wang, Kai Wu","doi":"10.1038/s44306-024-00031-6","DOIUrl":"10.1038/s44306-024-00031-6","url":null,"abstract":"In the past decade, there has been a significant rise in the development of novel spintronic device architectures specifically designed to meet the demands of diverse biomedical applications. These advancements have notably focused on enhancing various bioassay detection techniques, including magnetocardiography and neural signal recording. Through collaboration within the spintronics community, these devices are rapidly transitioning from laboratory prototypes to practical applications, catering to diverse biomedical applications and benefiting both researchers and medical practitioners alike. In this review, we comprehensively explore the biomedical applications of spintronic devices, due to their inherent sensitivity to external magnetic fields, ease of fabrication into large arrays of nano/micro-sized devices within confined spaces, resilience under harsh environmental conditions, and high repeatability. Established spintronics devices that exploit various magnetoresistive effects have already been extensively deployed as magnetic biosensors for disease diagnosis, medical imaging, and bio-magnetic field detection, offering superior sensitivity and robustness. This review aims to provide peers with an up-to-date overview of spintronic devices in biomedical contexts while also commenting on future research trends and challenges. With advancements in nano/microfabrication techniques enhancing device robustness and magnetic field sensitivity, it is foreseeable that these spintronic devices could catalyze revolutionary transformations in healthcare.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-23"},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00031-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141537070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-02DOI: 10.1038/s44306-024-00028-1
Ryan Bailey-Crandell, Warren L. B. Huey, Archibald J. Williams, Wenyi Zhou, Joshua E. Goldberger, Roland K. Kawakami
CrxPt1−xTe2 is a recently developed van der Waals magnetic alloy noted for its stability under ambient conditions. Here, we report the emergence of an exchange bias effect in CrxPt1−xTe2, without typical exchange bias sources such as an adjacent antiferromagnetic layer. We find that the exchange bias is present for x = 0.45 and absent for x = 0.35, which is correlated to the presence of a Cr modulation where the Cr concentration alternates each vdW layer (modulation period of 2 layers) for x ≥ 0.4. We perform Monte Carlo simulations utilizing exchange parameters from first-principles calculations, which recreate the exchange bias in hysteresis loops of Cr0.45Pt0.55Te2. From our simulations, we infer the source of exchange bias to be magnetic moments locked into free energy minima that resist magnetization reversal. This work presents a way to introduce desirable magnetic properties to van der Waals magnets.
CrxPt1-xTe2 是最近开发的范德华磁性合金，因其在环境条件下的稳定性而备受关注。在这里，我们报告了在 CrxPt1-xTe2 中出现的交换偏压效应，而没有典型的交换偏压源，如相邻的反铁磁层。我们发现在 x = 0.45 时存在交换偏压，而在 x = 0.35 时则不存在交换偏压，这与存在铬调制有关，在 x ≥ 0.4 时，铬浓度会交替出现在每个 vdW 层（调制周期为 2 层）。我们利用第一原理计算得出的交换参数进行蒙特卡罗模拟，再现了 Cr0.45Pt0.55Te2 磁滞环中的交换偏置。根据模拟结果，我们推断交换偏压的来源是被锁定在自由能最小值的磁矩，这些磁矩会抵制磁化反转。这项研究提出了一种为范德华磁体引入理想磁性的方法。
{"title":"Emergence of exchange bias in van der Waals magnetic alloy CrxPt1−xTe2","authors":"Ryan Bailey-Crandell, Warren L. B. Huey, Archibald J. Williams, Wenyi Zhou, Joshua E. Goldberger, Roland K. Kawakami","doi":"10.1038/s44306-024-00028-1","DOIUrl":"10.1038/s44306-024-00028-1","url":null,"abstract":"CrxPt1−xTe2 is a recently developed van der Waals magnetic alloy noted for its stability under ambient conditions. Here, we report the emergence of an exchange bias effect in CrxPt1−xTe2, without typical exchange bias sources such as an adjacent antiferromagnetic layer. We find that the exchange bias is present for x = 0.45 and absent for x = 0.35, which is correlated to the presence of a Cr modulation where the Cr concentration alternates each vdW layer (modulation period of 2 layers) for x ≥ 0.4. We perform Monte Carlo simulations utilizing exchange parameters from first-principles calculations, which recreate the exchange bias in hysteresis loops of Cr0.45Pt0.55Te2. From our simulations, we infer the source of exchange bias to be magnetic moments locked into free energy minima that resist magnetization reversal. This work presents a way to introduce desirable magnetic properties to van der Waals magnets.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00028-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141537074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-28DOI: 10.1038/s44306-024-00023-6
Daegeun Jo, Dongwook Go, Gyung-Min Choi, Hyun-Woo Lee
One of the ultimate goals of spintronics is to realize an efficient electrical manipulation of spin for high-speed and low-power nanodevices. A core ingredient for achieving this goal is the relativistic interaction between the electron’s orbital motion and spin, but the properties of the orbital angular momentum itself have remained largely unexplored. However, recent theories and experiments have uncovered that electrons may acquire nonvanishing orbital angular momentum when an external electric field is applied, even without the spin–orbit coupling. These findings have spurred the emergence of a burgeoning field known as orbitronics, which harnesses the orbital angular momentum to manipulate magnetic devices. In this Review, we provide an overview of the recent developments in orbitronics and discuss their implications for spintronics. We then outline future avenues of research at the intersection of spintronics and orbitronics.
{"title":"Spintronics meets orbitronics: Emergence of orbital angular momentum in solids","authors":"Daegeun Jo, Dongwook Go, Gyung-Min Choi, Hyun-Woo Lee","doi":"10.1038/s44306-024-00023-6","DOIUrl":"10.1038/s44306-024-00023-6","url":null,"abstract":"One of the ultimate goals of spintronics is to realize an efficient electrical manipulation of spin for high-speed and low-power nanodevices. A core ingredient for achieving this goal is the relativistic interaction between the electron’s orbital motion and spin, but the properties of the orbital angular momentum itself have remained largely unexplored. However, recent theories and experiments have uncovered that electrons may acquire nonvanishing orbital angular momentum when an external electric field is applied, even without the spin–orbit coupling. These findings have spurred the emergence of a burgeoning field known as orbitronics, which harnesses the orbital angular momentum to manipulate magnetic devices. In this Review, we provide an overview of the recent developments in orbitronics and discuss their implications for spintronics. We then outline future avenues of research at the intersection of spintronics and orbitronics.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-9"},"PeriodicalIF":0.0,"publicationDate":"2024-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00023-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141537073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-28DOI: 10.1038/s44306-024-00022-7
Tatjana Thomas, Yassine Agarmani, Steffi Hartmann, Mark Kartsovnik, Natalia Kushch, Stephen M. Winter, Sebastian Schmid, Peter Lunkenheimer, Michael Lang, Jens Müller
Ferroelectricity, where electronic degrees of freedom determine the polar order—thereby enabling fast switching and phase control—is an important research field in current condensed-matter physics. Using a combination of resistance noise and dielectric spectroscopy we investigate the nature of relaxor-type electronic ferroelectricity in the organic conductor κ-(BETS)2Mn[N(CN)2]3, a system that represents a wider class of materials of correlated electron systems for which functionalities for organic spintronics recently have been discussed. The two complementary spectroscopies reveal a distinct low-frequency dynamics on different length scales, namely (i) an intrinsic relaxation that is typical for relaxor ferroelectrics which classifies the system as a possible new multiferroic, and (ii) two-level processes which we identify as fluctuating polar nanoregions (PNR), i.e., clusters of quantum electric dipoles that fluctuate collectively. The PNR preform above the metal insulator (MI) transition. Upon cooling through TMI, a drastic increase of the low-frequency 1/f-type fluctuations and slowing down of the charge carrier dynamics is accompanied by the onset of strong non-equilibrium dynamics indicating a glassy transition of interacting dipolar clusters. The freezing of PNR and non-equilibrium dynamics is suggested to be a common feature of organic relaxor-type electronic ferroelectrics.
{"title":"Slow and non-equilibrium dynamics due to electronic ferroelectricity in a strongly-correlated molecular conductor","authors":"Tatjana Thomas, Yassine Agarmani, Steffi Hartmann, Mark Kartsovnik, Natalia Kushch, Stephen M. Winter, Sebastian Schmid, Peter Lunkenheimer, Michael Lang, Jens Müller","doi":"10.1038/s44306-024-00022-7","DOIUrl":"10.1038/s44306-024-00022-7","url":null,"abstract":"Ferroelectricity, where electronic degrees of freedom determine the polar order—thereby enabling fast switching and phase control—is an important research field in current condensed-matter physics. Using a combination of resistance noise and dielectric spectroscopy we investigate the nature of relaxor-type electronic ferroelectricity in the organic conductor κ-(BETS)2Mn[N(CN)2]3, a system that represents a wider class of materials of correlated electron systems for which functionalities for organic spintronics recently have been discussed. The two complementary spectroscopies reveal a distinct low-frequency dynamics on different length scales, namely (i) an intrinsic relaxation that is typical for relaxor ferroelectrics which classifies the system as a possible new multiferroic, and (ii) two-level processes which we identify as fluctuating polar nanoregions (PNR), i.e., clusters of quantum electric dipoles that fluctuate collectively. The PNR preform above the metal insulator (MI) transition. Upon cooling through TMI, a drastic increase of the low-frequency 1/f-type fluctuations and slowing down of the charge carrier dynamics is accompanied by the onset of strong non-equilibrium dynamics indicating a glassy transition of interacting dipolar clusters. The freezing of PNR and non-equilibrium dynamics is suggested to be a common feature of organic relaxor-type electronic ferroelectrics.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-11"},"PeriodicalIF":0.0,"publicationDate":"2024-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00022-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141537086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-28DOI: 10.1038/s44306-024-00026-3
Cody Trevillian, Vasyl Tyberkevych
A general approach to quantify chirality, or absence of parity symmetry, of spin waves has been developed and applied to spin waves propagating in obliquely magnetized ferromagnetic films. Using theoretical arguments and numerical calculations, it is shown that, upon increasing spin wave wavevector, initially achiral spin waves develop chiral properties through the “parity exchange” mechanism, which implies, in particular, that chiral spin waves appear in pairs. The most striking example of the parity exchange mechanism is the simultaneous formation of two chiral waves: the magnetostatic surface wave and the recently discovered heterosymmetric spin wave, which were previously considered independent of each other. Another manifestation of the parity exchange is the formation of strongly chiral waves near the anti-crossings of spin wave branches of unequal symmetry. These findings illustrate viable paths to engineering spin wave systems with prescribed chiral spectra that had not previously been considered.
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